Portion of an air treatment unit



FIG. 1 is a front and right side perspective view of a portion of an air treatment unit according to our new design;

FIG. 2 is a front side elevational view of the design of FIG. 1;

FIG. 3 is a left side elevational view of the design of FIG. 1, the right side being a mirror image of the left side;

FIG. 4 is a top plan view of the design of FIG. 1; and,

FIG. 5 is a rear elevational view of the design of FIG. 1.

The bottom of the air treatment unit is plain and unornamented and forms no part of the claimed design. The broken lines, including those showing the bottom portion, the top portion, the front side grill openings, controls and display, and the rear side grill openings, are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a portion of an air treatment unit, as shown and described. 